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## [Axiom-developer] [#180 bug #9216 differentiating sums with respect to a

**From**: |
kratt6 |

**Subject**: |
[Axiom-developer] [#180 bug #9216 differentiating sums with respect to a bound is wrong] |

**Date**: |
Thu, 23 Jun 2005 05:52:58 -0500 |

Changes
http://page.axiom-developer.org/zope/mathaction/180Bug9216DifferentiatingSumsWithRespectToABoundIsWrong/diff
--
??changed:
-From BillPage Wed Jun 22 13:57:40 -0500 2005
-From: Bill Page
-Date: Wed, 22 Jun 2005 13:57:40 -0500
-Subject: (new) bug #9216 differentiating sums with respect to a bound is wrong
-Message-ID: <address@hidden>
differentiating sums with respect to a bound is wrong
The function $n\mapsto\sum_{k=1}^n f(k,n)$ is well defined only for integral
values of $n$ greater than or equal to zero. There is not even consensus how to
define this function for $n<0$. Thus, it is not differentiable. The fix I
propose is thus
<a href="dvdpatch2.patch">dvdpatch2.patch</a>
??changed:
-+ ddiff l ==
-+ prefix(sub(D::O, third(l)::O), [eval(first(l), second(l), third(l))::O])
-+
-and
-+ setProperty(opdiff, SPECIALDISP, ddiff@(List F -> O) pretend None)
+ ddiff l ==
+ prefix(sub(D::O, third(l)::O), [eval(first(l), second(l),
third(l))::O])
+
and::
+ setProperty(opdiff, SPECIALDISP, ddiff@(List F -> O) pretend None)
--
forwarded from http://page.axiom-developer.org/zope/mathaction/address@hidden